There are a number of applications for liquid dispensers which dispense a controlled amount of the liquid. In paint stores, paint pigments are mixed accurately to a formula to create various color tones. Therefore, it is necessary to have a dispenser which can dispense controlled amounts of different color pigments easily and quickly. Existing paint pigment dispensers are of two general classes. The first class is a multi-channel gear pump. In this device a gear exerts a constant pressure to a pump piston and a valve is opened for a known time. Since pressure is controlled by the gear and the time the valve is open is known, an approximately known amount of pigment is dispensed. The second class of existing systems is a multi-channel device in which a plurality of pistons and valves are provided which are actuated by motors. Since each piston displaces a known volume, a known amount of pigment is dispensed. While this class of system is precise, it is inordinately expensive to manufacture. pigment is dispensed. While this class of system is precise, it is inordinately expensive to manufacture.
Both of these systems seem to have disadvantages as far as accuracy is concerned. Both are predominately mechanical so as to be both expensive and unreliable. Also, neither are easily amenable to computer control. Therefore, it would be desirable to have a liquid dispenser which can accurately dispense a plurality of different liquids, which is relatively inexpensive, and which is amenable to computer control.